Cathodic electrodeposition coating compositions containing bismuth compounds and dicarboxylic acids, production and use thereof

Abstract

Waterborne cathodic electrodeposition (CED) coating compositions comprising resin solids and optionally pigments, fillers and conventional coating additives, wherein said CED coating compositions comprise at least one bismuth compound in a quantity of 0.1 to 2.5 wt. %, calculated as bismuth and relative to resin solids content, together with at least one dicarboxylic acid selected from among acyclic dicarboxylic acids with 3 to 7 carbon atoms and dicarboxylic acids with 8 to 10 carbon atoms comprising a cyclic structural unit in a quantity of 3 to 15 equivalent-%, relative to the acid equivalents present in the CED coating composition.

1. Waterborne cathodic electrodeposition (CED) coating compositions comprising resin solids and optionally pigments, fillers and conventional coating additives, wherein said CED coating compositions comprise at least one bismuth compound in a quantity of 0.1 to 2.5 wt. %, calculated as bismuth and relative to resin solids content, together with at least one dicarboxylic acid in a quantity of 3 to 15 equivalent %, relative to 100 equivalent % of acid present in the CED coating composition, wherein the at least one dicarboxylic acid is selected from the group consisting of acyclic dicarboxylic acids with 3 to 7 carbon atoms and dicarboxylic acids with 8 to 10 carbon atoms comprising a cyclic structural unit. 
     
     
       2. The CED coating compositions of  claim 1 , wherein the proportion of the at least one bismuth compound is 0.5 to 2 wt. %, calculated as bismuth and relative to resin solids content. 
     
     
       3. The CED coating compositions of  claim 1 , wherein the at least one bismuth compound is selected from the group consisting of bismuth chelate complexes, bismuth oxide, bismuth hydroxide and bismuth salts. 
     
     
       4. The CED coating compositions of  claim 1 , wherein the at least one bismuth compound is selected from the group consisting of bismuth lactate, bismuth dimethylolpropionate, bismuth amidosulfonate and bismuth hydrocarbylsulfonates. 
     
     
       5. The CED coating compositions of  claim 1 , wherein 100 equivalent % of acid present in the CED coating composition is equal to 20 to 70 milliequivalents of acid per 100 g of resin solids content. 
     
     
       6. The CED coating compositions of  claim 1 , wherein the resin solids content comprises a system which self-crosslinks or externally crosslinks by reaction of groups comprising active hydrogen with blocked isocyanate groups. 
     
     
       7. A process comprising cathodic electrodepositing a coating of the CED coating composition according to  claim 1  on an electrically conductive substrate. 
     
     
       8. A process according to  claim 7 , wherein the substrate comprises a substrate selected from the group consisting of automotive bodies and body parts.